Join Date: May 2004
Location: SIN (LEJ once a year)
Programs: SQ, LH, BA, IHG Diamond AMB, HH Gold, SLH Indulged, Accor Gold, Hyatt Discoverist
Posts: 8,813
They can be used for future travel. Just once you book for a date beyond the expiration of the miles, if you cancel then the miles won't be coming back and are forfeit. So make sure it is a route where you definitely want to go to in next 1 year (from day of ticket issuance).